Published in PLOS One on 2026-06-05, this study is presented as an attributed evidence briefing. The excerpts below are the original researchers’ words, reproduced under their Creative Commons Attribution licence. Health Signal has selected the abstract and, where needed, opening background paragraphs; the complete methods, results, limitations and references remain in the linked paper.
Original authors: Ligabaw Worku, Amha Kebede, Ayalew Jejaw Zeleke, Saron Fekadu, Melat Abdo, Tigist Atele, Netsanet Worku, Mulugeta Aemero
Source: PLOS One • DOI 10.1371/journal.pone.0350942
Read the complete primary study ↗ · Creative Commons Attribution licence
From the researchers
Abstract
Anopheles mosquitoes are the main vectors of malaria. Effective vector control depends on understanding their species composition, behavior, distribution, and insecticide resistance. This study investigated Anopheles species composition, susceptibility to deltamethrin, and the frequency of knockdown resistance (kdr) mutations in Maksegnit and Gendawuha, Northwest Ethiopia.
Anopheles larvae and pupae were collected from breeding sites during the rainy and post-rainy seasons and reared to adults under field insectary conditions following WHO guidelines. In addition, adult mosquitoes were collected from houses near larval habitats. Only field-derived mosquito populations were used in this study. Adult females (3–5 days old) reared from field-collected larvae were tested for susceptibility to 0.05% deltamethrin using WHO bioassays. Based on bioassay outcomes, mosquitoes were classified as phenotypically susceptible (died after exposure) or resistant (survived exposure), while field-collected adults represented an unexposed group. A total of 480 mosquitoes (160 resistant, 160 susceptible, and 160 field-collected unexposed adults) were subjected to genomic DNA extraction. Species identification and detection of knockdown resistance (kdr) mutations (L1014F and L1014S) were performed using PCR.
WHO bioassays conducted on 776 mosquitoes revealed confirmed resistance to deltamethrin, with mortality rates ranging from 48.5% to 72.5% (overall resistance: 37.5%). Resistance intensity exhibited significant variation, peaking after the rainy season and showing a higher prevalence in Maksegnit compared to Gendawuha (p < 0.05). Molecular identification of 480 mosquitoes showed that Anopheles arabiensis was the predominant species (93%, 446/480), followed by An. pharoensis (6%, 29/480) and An. stephensi (1%, z/480), with the latter detected for the first time in Gendawuha. Regarding kdr mutation status, genotypic analysis showed that the L1014F mutation was the predominant allele, particularly among phenotypically resistant mosquitoes (67.8%), while lower frequencies were observed in susceptible (45.8%) and unexposed field-collected groups (61.4%). Conversely, the L1014S mutation was detected at low frequency (≤12.3%) and was restricted exclusively to the Maksegnit population.
Anopheles arabiensis predominated, with confirmed resistance to deltamethrin, particularly in the post-rainy season. The L1014F kdr mutation was prevalent, while L1014S kdr mutation was rare. Detection of Anopheles stephensi highlights emerging risks, underscoring the need for season-specific resistance monitoring and integrated control strategies.
Background
Anopheles mosquitoes are the main vectors of malaria globally, transmitting Plasmodium parasites that lead to high morbidity and mortality, particularly in sub-Saharan Africa where the disease burden is greatest [1]. Understanding their biology, behavior, and distribution is critical for designing targeted vector control strategies aimed at reducing transmission [2]. Effective management of these mosquito populations remains a significant public health challenge, emphasizing the need for ongoing surveillance, resistance monitoring, and integrated control approaches [3]. Knowledge of species composition, seasonal patterns, and geographical distribution is essential for implementing precise interventions tailored to local vector ecology, such as insecticide application and habitat modification, timed to peak mosquito activity, and focused in high-risk areas to minimize transmission and enhance public health outcomes [4–8].
Reading this evidence
Use the full paper to check the study design, participant selection, comparator and outcome definitions before drawing a practical conclusion. An association does not by itself show cause and effect. A reported performance measure needs its denominator and uncertainty. A finding from a particular facility, sample or time period should retain that scope when it is discussed elsewhere.
This briefing makes the source accessible within the wider public health desk. It does not assess an individual patient or certify a product. When considering relevance to another health system, examine the original authors’ account of context and limitations, then seek local implementation evidence. The related reporting below provides other studies to read alongside this one; it is a topic connection, rather than a claim that their results are directly comparable.
© 2026 Ligabaw Worku, Amha Kebede, Ayalew Jejaw Zeleke, Saron Fekadu, Melat Abdo, Tigist Atele, Netsanet Worku, Mulugeta Aemero. Excerpts reproduced under CC BY. Selection, formatting and contextual notes by Health Signal. The researchers are the authors of the source study, not members of Health Signal’s staff.
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